Field of the Invention and Related Art Statement
This invention relates to an electronic endoscope tip provided with a solid state imaging device.
Recently, instead of an optical endoscope for observing a body interior image by using fibers, an electronic endoscope provided with such solid state imaging device as a CCD (charge coupled device) in the tip of an insertable part has come to be developed. In such endoscope, it is desired to make the tip small in the diameter from the necessity of reducing the pain of the patient when it is inserted.
The above mentioned solid state imaging device is generally rectangular or square and therefore will occupy a comparatively large space in case it is contained in the tip of an insertable part. Therefore, for example, in the publication of Japanese utility model laid open No. 184017/1985, it is suggested that the optical axis of an objective optical system is deflected by such optical device as a prism and is led to a solid state imaging device provided in parallel with the lengthwise direction of an insertable part to make the tip of the insertable part small in the diameter.
However, in the above mentioned prior art example, a substrate for mounting an electronic part is provided on the side reverse to such optical device as a prism so as to be overlapped with the solid state imaging device and therefore the thickness of the part in which the prism, solid state imaging device and substrate are arranged will become so large that there has been a defect that the tip can not be made small enough in the diameter.
Also, in Japanese patent laid open No. 241011/1985 or U.S. Pat. No. 4,573,450, it is suggested that the optical axis of an objective optical system is deflected substantially at right angles by an optical device and a solid state imaging device is arranged substantially in parallel with the inserting axis of an endoscope to make the tip small in the diameter.
These two prior art examples have the same defect as of the first prior art example.
Now, in the tip of an endoscope, not only a solid state imaging device chip but also a clock generating integrated circuit for driving the solid state imaging device and an amplifier for amplifying the image output from the solid state imaging device must be incorporated. In such case, if the solid state imaging device chip is once packaged and is connected with a substrate fitted with the other electronic part, a space for the connecting part will have to be provided, the endoscope tip will become thick and the rigid tip part will become long.
In the above mentioned three prior art examples, if the electronic part is fitted, the outside diameter of the rigid tip will have to be made larger, a great pain will be forced to the patient when the tip is inserted into the body cavity and the insertable cases will be restricted.